1. Field of the Invention
This invention relates to a test piece for the detection of occult blood. More particularly, this invention relates to a stable test piece for easy detection of blood and other peroxidatively active substance in body fluid.
2. Description of Prior Arts
Presence of blood or peroxidatively active hemoglobin in body fluid such as, for urine, feces or vomit may be regarded as an indication of a certain disease such as inflammation ulcer or tumor in the stomach, the kidney, the intestines and other urinary organs. In this case, therefore, it is clinically very important that diagnosis or therapy should be given with minimum loss of time. For this purpose, it is necessary that the blood or peroxidatively active substance present in the body fluid should be detected accurately.
Virtually all the conventional methods adopted for the detection of occult blood in given body fluids have utilized the peroxidative activity of occult blood. For example, a test piece has been prepared by impregnating a carrier such as filter paper with an organic hydroperoxide and an organic color-forming indicator as a chromogen. When peroxidatively active blood or free hemoglobin comes into contact with this test piece, it decomposes the aforementioned hydroperoxide with liberation of oxygen and the produced oxygen oxidizes the organic color-forming indicator and causes it to assume a color.
The organic color-forming indicator contained in the test piece possesses an oxidative power and the organic hydroperoxide also contained in the test piece is a reactive substance and, therefore, is potentially incompatible with the indicator. Since these incompatible components coexist in the test piece, they are essentially readily reactive with each other. Thus, the test piece does not withstand prolonged preservation. With a view to inhibiting this unwanted reaction of the two components during the storage of the test piece, it has been proposed to incorporate in the test piece a stabilizer. Examples of stabilizers proposed to date include di- or trimorpholide phosphate type compounds (U.S. Pat. No. 3,853,471), amine salt of organic hydroperoxide (U.S. Pat. No. 4,017,261), and boric esters (U.S. Pat. No. 4,071,321). Among the conventional stabilizing methods is included a method which involves microcapsulating an organic hydroperoxide with a glutinous substance such as gelatin.
The conventional techniques adopted for the incorporation of stabilizers have invariably been aimed at stabilizing the potentially incompatible reagents (organic hydroperoxide and organic color-forming indicator) by preventing them from quickly mingling with each other. Di- or trimorpholide phosphate type compounds are primarily insectifuges (contraceptives for insects). Because of their violent actions, therefore, their manufacture is hazardous and their handling calls for the utmost care. Amine salts of organic hydroperoxides are highly volatile. Test pieces containing such compounds, therefore, readily affect other test papers placed nearby. In the case of boric esters, since they are used in combination with dimethyl sulfoxide, for example, the test pieces incorporating these compounds similarly affect other test papers placed nearby. Thus, the conventional stabilizers have their demerits. In the case of the microcapsulation of an organic hydroperoxide, there is entailed a disadvantage that the microcapsule, on aging, becomes sufficiently rigid as to jeopardize the readiness of the reaction and impair the uniformity of the reaction in the test piece, with the result that the color is formed unevenly. Since the conventional reagents and test pieces have been unstable as described above, it has occurred rather frequently that the colors developed by the test pieces defy accurate discernment.
An object of this invention, therefore, is to provide a novel test piece for the detection of occult blood in body fluids.
Another object of this invention is to provide a test piece for the detection of occult blood, which is possessed of improved color sensitivity for the sake of easy detection.